Enabling additional USARTS for STM32 in Arduino - arduino

Question

I am trying building a project that requires me to use 6 UART connections. For this I have chosen the STM32F030CCT6 MCU, which supports 6 USARTs. I have gotten all 6 to work in the STM CubeIDE, but have decided to switch over to the Arduino IDE because I would like to use a few libraries.
In Arduino, I am using the latest Arduino_Core_STM32 api.
The api doesnt specify the suport for this exact chip, but it lists supports the STM32F030C8T6 chip, which for all intents is the same, with the only difference that it supports only 3 USARTS. I have tried using both HardwareSerial and SoftwareSerial libraries to add uarts, but when I add more then 2 UARTS the code compiles, uploads and executes until the first UART and then just "hangs" until I reset the chip.
My question is if I can somehow modify the library/get a different library that supports all 6 USARTS of this chip.
Alternativly, is it possible to use the working code generated in MXCube in Arduino and use the USART that way?
Or is this just a problem with Arduino_Core_STM32?
used settings to program
code:
#include <EthernetENC.h>
#include <HardwareSerial.h>
#include <SoftwareSerial.h>
HardwareSerial mySerial1(PA5,PA4); // compiles, can also use (USART1)
HardwareSerial mySerial2(PB11,PB10); // compiles, can also use (USART2)
HardwareSerial mySerial3(PA10,PA9); // compiles
void setup() {
pinMode(PB15, OUTPUT); //CP WRITE 34
digitalWrite(PB15, LOW);
}
void loop() {
digitalWrite(PB15, HIGH);
delay(500);
digitalWrite(PB15, LOW);
delay(500);
mySerial1.begin(9600);
mySerial1.println("Hello, world?");
mySerial1.end();
mySerial2.begin(9600);
mySerial2.println("Hello, world2?");
mySerial2.end();
mySerial3.begin(9600);
mySerial3.println("Hello, world3?");
mySerial3.end();
}

Answer 1

Thank you to everyone for the insight, learned a lot of new things.
I managed to get all 6 USARTS to work by creating a new board variant.
The port map files were already present for this board (and many others )in the
AppData\Local\Arduino15\packages\STMicroelectronics\hardware\stm32\2.3.0\variants folder.
I just edited the boards.txt file to add the F030CCT folder and created a .ld file in MX cube and added it to the folder. The board now behaves like it should and all the pins and functions work great.
I just changed the top part of the code to:
HardwareSerial SerialX(USART1);
HardwareSerial SerialY(USART2);
HardwareSerial Serialz(USART3);
HardwareSerial SerialX2(USART4);
HardwareSerial SerialY2(USART5);
HardwareSerial Serialz2(USART6);